Electronic devices equipped with touch panel displays, such as smart phones or tablets have widely been used. The electronic device can be generally set to enter a lock mode when the device is not operated for a predetermined time. After the shift to the lock mode, the touch panel display is also turned off. Upon detection of a touch operation and the like on the touch panel display by a user in the lock mode, the touch panel display is turned on to display an entry screen to prompt the user to make an entry for cancelling the lock mode. Upon detection of a user's entry of a password, a passcode or a pattern which is registered in advance, the electronic device exits from the lock mode.
When the device is set to enter the lock mode within a short period of time, the user is forced to often enter the password, the passcode or the pattern to cancel the lock mode, which results in an increase in user's load. To reduce such load, many users set their devices not to enter the lock mode or set a long period of time to enter the lock mode.
Meanwhile, the following setting is also popular: when not operated for a predetermined time, the device enters a sleep mode before entering a lock mode; and then enters the lock mode if not operated for another predetermined time after the shift to the sleep mode. If a user wants to cancel the sleep mode, the user has only to perform a touch operation on the touch panel display. A related technique is disclosed by Japanese Laid-open Patent Publication No. 2009-272996, for example.